Urinary System

Urinary System Outline:

Kidneys Kidneys are two bean shaped organs lying close to the lumbar spine on either side, they are multifunction organ, form urine and control its concentration
Ureters Two hollow muscular tubes one arising from each kidney and ending at the urinary bladder, connect kidneys to the bladder
Urinary Bladder Stores urine before it is excreted from the body, hollow muscular and distensible organ, sits on the pelvic floor.
Urethra A tube connecting the urinaly bladder to the genitals for excretion
Functions Excretion of nitrogenous wastes, Osmoregulation, Acid-Base balance

Introduction to Urinary System:

Urinary System

Urinary System (SOURCE: Jordi March i Nogué/Wikipedia)

Urinary system is also known as excretory system of human body. It is the system of production, storage and elimination of urine. Formation and elimination of urine is important for human body because urine contains nitrogenous wastes of the body that must be eliminated to maintain homeostasis. Nitrogenous wastes are formed by metabolic activities in the cells. These nitrogenous wastes along with excess of salts and water are combined in the kidneys to form urine. Urinary system is important for keeping the internal environment of the body clean. Urinary system maintains proper homeostasis of water, salts and nitrogenous wastes.

Components of urinary system:

Human urinary system consists of two kidneys, two ureters, a urinary bladder, a urethra and sphincter muscles.

  • KIDNEYS: Kidneys are the major organs of urinary system. Formation of urine takes place in kidneys which are two bean shaped organs lying close to the lumbar spine, one on each side of the body.
  • URETERS: These are muscular tubes extending from the kidneys to the urinary bladder. Urine flows in these tubes from kidney to the urinary bladder.
  • URINARY BLADDER: Urinary Bladder collects urine before it is excreted from the body. Urinary bladder is a hollow muscular and elastic organ siting on the pelvic floor
  • URETHRA: Urethra is a tube that connects the urinary bladder to the external genitalia for elimination from the body.
  • SPHINCTER MUSCLES: There are two sphincter muscles to control the elimination of urine from human body. The external of the two muscles is striated and is under voluntary control of the body.

Functions of urinary system:

As stated above, urinary system is the excretory system of human body. It performs the following important functions;

  1. FORMATION AND ELIMINATION OF URINE: The main function of urinary system is formation and elimination of urine. Urine is formed by the kidneys in 3 steps; 1) Glomerular Filtration, 2)Tubular reabsorption, and 3)Tubular secretion. For more details on the process of formation of urine, visit “”.
  2. OSMOREGULATION: Kidneys are important osmoregulatory organs of human body. THey maintain salt and water balance of the body. If the concentration of salt or water is increased above normal, kidney will excrete the excess amount. If the concentration is decreased, kidneys will reduce the loss of water and salts in urine.
  3. ACID BASE BALANCE: Kidneys are important regulators of pH of body fluids. Kidneys keep the pH balanced within a very small range and provide an optimum environment for all processes of life.

Learn urinary system at MANanatomy.com:

The urinary system is explained in the following sections: